Big Maxx heater question

[Reit38]

Anyone else using a big Maxx heater got mine hooked up now when it tries to come up to heat it runs for awhile then shuts off then runs for awhile then shuts off didn't know if it should be a continuous heat till it hits its set temp or if it should cycle like that. The fan motor continuously run even though the flame shuts off

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[D45]

Doesn't sound like it's working right

NG or L.P.?

 

[Reit38]

Lp

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[LS6 Tommy]

Almost sounds like the a limit is tripping, but they're usually manual reset.

Tommy

 

[38Chevy454]

Agree, sounds like some sensor is shutting off gas. Should run continuously until thermostat shuts off. How long does it run before shutting off?

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[Reit38]

I just realized I think I made a big mistake. I hung the heater last year and just got lp hooked up and never converted the heater over to lp. I'm assuming this is the problem but also hoping I didnt screw anything up in the heater itself.

I found the orifices [ think that's what they're called] in a in the paperwork. Anything special to convert it over?

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[The Cobbler]

is there a kit for the gas valve? you need to adjust the pressure in the gas valve too

 

[TractorJeff]

It doesn't take long. I did mine sitting on a Bench, had the Manual, Read it once. then followed the directions. Set the LP pressure after changing the Regulator parts. All pretty simple!

 

[Reit38]

Got everything changed over for Lp.

Burner still runs for approximately 30sec then shuts off, fan continues to run. Burner kicks back on for another 30sec the kicks off.

Whole unit shuts off when gets up to temp

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[Showkey]

How did you measure the LP pressure and was the pressure adjusted to what setting ?

Are there error codes flashing on the board ?

 

[Reit38]

Directions said 11 full turns

No codes showing

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[Showkey]

The instructions usually says something like 10.9” wc ( inches of water column)

Check gas line pressure with unit firing at maximum rate. A minimum of 5.0” w.c. for natural gas or 10.9” w.c. for LP/propane gas should be maintained for proper unit operation.

After line pressure has been checked and adjusted, check manifold pressure. Correct manifold pressure is shown on the unit rating plate. See pic for gas pressure adjustment screw location. A natural gas to LP/propane gas changeover kit is required to convert unit. Refer to installation instructions provided with changeover kit for conversion procedure.

Does it seem to roar or give any indication it’s over fired, running too hot ????

 

[Reit38]

The instructions usually says something like 10.9” wc ( inches of water column)

Check gas line pressure with unit firing at maximum rate. A minimum of 5.0” w.c. for natural gas or 10.9” w.c. for LP/propane gas should be maintained for proper unit operation.

After line pressure has been checked and adjusted, check manifold pressure. Correct manifold pressure is shown on the unit rating plate. See pic for gas pressure adjustment screw location. A natural gas to LP/propane gas changeover kit is required to convert unit. Refer to installation instructions provided with changeover kit for conversion procedure.

Does it seem to roar or give any indication it’s over fired, running too hot ????

no it seems to run pretty quiet. Nice blue flames with orange tips

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[Showkey]

no it seems to run pretty quiet. Nice blue flames with orange tips

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Could it be under fired and the fan on switch is going off because of low temperature? Then heats backup up fan on ..........That would answer the on/off condition and no codes.

Under fired would be caused by lower than specified gas pressure.

 

[Gizzi]

If the burner is turning on and off during a call for heat, you may have poor carry over on the burners due to incorrect gas pressure, dirty burners (sooted) or a flame sense issue. Easiest thing to do is clean the flame sensor with some emery cloth or a wire brush and see if that corrects the problem.

 

[Showkey]

Flame sensor error ( not being satisfied) would cause a code on the board. Also likely cause a lock out after three starts with the error.

 

[Gizzi]

Flame sensor error ( not being satisfied) would cause a code on the board. Also likely cause a lock out after three starts with the error.

I agree that it should cause an error code under normal circumstances. I have seen odd instances where flame and pressure switch issues for some reason won't cause a fault indication. Hard to troubleshoot without seeing the unit run. Not sure if the board on the Big Maxx heaters use a timer to turn the fan on or a bimetal switch. I figure to try the easiest things first in this case.

 

[spudley]

Check (and set) your pressure with a manometer. Eliminates the guesswork.

 

[rustyzman]

Silly question, but are you not getting enough vapor from your tank? What size tank are you using to feed it? I had a bad tank regulator early on with mine that was causing some fuel starvation issues and poor heating.

When the heat shuts down but the fan keeps running, can you hear the ignitor fire back up? Might be an indicator of loss of fuel supply with no codes.

Just a thought.

 

[Showkey]

Silly question, but are you not getting enough vapor from your tank? What size tank are you using to feed it? I had a bad tank regulator early on with mine that was causing some fuel starvation issues and poor heating.

When the heat shuts down but the fan keeps running, can you hear the ignitor fire back up? Might be an indicator of loss of fuel supply with no codes.

Just a thought.

Not silly.........especially if it’s a 20# tank that’s cold and half full.

Gas pressure reading while heater is in use is critical information.

 

[Reit38]

Tank is a 250gal. Tank and regulator were installed by fuel company

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[Gizzi]

You're likely going to need a manometer to troubleshoot any further. According to Mr Heater, gas line pressure on the INLET of the gas valve needs to be at least 13" WC. On the outlet of the gas valve, under fire, the burner/manifold pressure should be right around 10.4" WC. You may have too much fuel pressure drop.

 

[TractorJeff]

Post 11 states 11 turns?
NOPE!
Need a Manometer to measure proper Inlet /Outlet Pressures.
Even a pressure gauge is better than nothing.........